Polyesters, especially polyalkylene terephthalates, and polyamides, especially nylon 6 and nylon 66, have excellent physical and chemical properties and have been widely used for resins, films and fibers. In particular, polyester and polyamide fibers have relatively high melting points, and can attain high orientation and crystallinity. Accordingly, polyesters and polyamides have excellent fiber properties such as chemical, heat and light stability, and high strength.
However, polyesters, especially polyester fibers, are difficult to dye. The molecular structure and the high levels of orientation and crystallinity that impart desirable properties to the polyester also contribute to a resistance to coloration by dye compounds. Also contributing to the difficulty in dyeing polyester is the characteristics that polyesters, unlike protein fibers, do not have dye sites within the polymer chain that are reactive to basic or acid dye compounds. Although polyamides are not as difficult to dye as polyesters, one or more dyeability additives are nevertheless commonly incorporated into polyamides, e.g., in order to selectively increase the affinity of the polyamide fibers for certain types of dyes, e.g., acidic or basic, or to selectively increase the resistance of the fibers to staining with certain types of staining agents.
It is known that that certain materials, such as aromatic sulfonates and their sodium salts, including the sodium salt of 5-sulfoisophthalic acid or the sodium salt of dimethyl 5-sulfoisophthalate, can be copolymerized with the polyester or polyamide as a means of conferring basic dyeability. Other cationic dyeability modifiers have also been disclosed. For example, Sakurai, U.S. Pat. No. 3,313,778, discloses a modified polyester which has linked to the main chain thereof a minor proportion of at least one organo sulfonic acid ester having the formula (X--SO.sub.2 --O).sub.n --Y, where n is an integer from 1 to 4; X is, e.g., an alkyl group of 1 to 12 carbon atoms; and Y is, e.g., a lower alkyl group, having one or two ester-forming functional groups, for example beta-carbomethoxyethyl methanesulfonate.
Further, poly(trimethylene terephthalate) has many properties that make it desirable for use in manufacturing fibers for textile applications, including improved recovery and resilience, as compared with poly(ethylene terephthalate). However, cationic dyeability modifiers that are particularly useful for improving the basic dyeability of poly(trimethylene terephthalate) have not been proposed.
It is desireable to provide a cationic dyeability modifier which can be incorporated into polyesters, especially poly(alkylene terephthalate), and polyamides, especially nylon 6 and nylon 66, to confer improved basic dyeability and which can be produced at lower cost than conventional cationic dyeability modifiers.
It is also desirable to provide a basic dyeable polyester, in particular poly(alkylene terephthalate), and more particularly poly(trimethylene terephthalate), which can be easily processed into fibers, films or other shaped articles and basic-dyed without the use of expensive cationic dyeability modifiers or additives, special solutions, and/or complicated application procedures.
It is also desireable to provide a basic dyeable polyamide, in particular nylon 6 or nylon 66, which can be easily processed into fibers, films or other shaped articles and basic-dyed without the use of expensive cationic dyeability modifiers or additives, special solutions, and/or complicated application procedures. The present invention provides such a cationic dyeability modifier and basic dyeable polyester and polyamide.